" ... if someone insists you can only sing songs from your own personal background, ..."

Here we go again! He didn't insist on any such thing! The Singers' Club (of which EM was a founder member), in London, at a particular time, had a POLICY which encouraged participating singers to sing songs from their own backgrounds. This was because, at the time, many British singers were singing mainly American songs and EM and the club wished to encourage singers to re-discover their own folk musical heritages. Seems to be perfectly reasonable to me. But if it doesn't seem reasonable to you it was years ago and applied to one club only - for God's sake, get over it!!!